BALTIMORE, MD (July 9, 2004) – In an effort to fully investigate groundwater contamination caused by a widely used gasoline additive, the Maryland Department of the Environment (MDE), the Harford County Health Department and ExxonMobil officials have agreed to expand their sampling of residential wells in the Upper Crossroads area.

Starting next week, 70 homes in the Orchard Lakes subdivision will be sampled for the gasoline additive methyl tertiary butyl ether, MTBE. In recent weeks, 233 homes were sampled as part of the investigation.

Groundwater trends are coming into focus as a result of preliminary geologic study. Expansion of the sampling area beyond a half-mile radius of the ExxonMobil station at MD Routes 152 and 162 is in response to these trends. The scientific data is still being developed and investigation and cleanup plans will be adjusted as the data is collected and examined.

“We share the public’s concern and are committed to ensuring that the contamination and public health issues in this case are fully resolved,” said MDE Deputy Secretary Jonas P. Jacobson.

The U.S. Environmental Protection Agency has concluded that there is no measurable health effect from low level MTBE exposure. EPA’s health advisory states that levels of contamination at or below 20 parts per billion (ppb) provide a large margin of safety from adverse health effects.

Dr. Andrew Bernstein, Health Officer for Harford County, advises, “Levels in and around 20 to 40 ppb are primarily issues of taste and smell and not cause for alarm.”

MDE is convinced that ExxonMobil station is responsible for at least part of the MTBE contamination present in the Upper Crossroads area. However, other sources are being considered and may be proved to have contributed to this issue. MDE intends to continue oversight of this investigation to ensure the protection of the environment, public health and safety.

MTBE replaced lead as an octane enhancer in gasoline and helps the fuel burn more completely, thereby reducing harmful tailpipe emissions from motor vehicles.

MTBE can become introduced into the environment, particularly water, from leaking underground and aboveground petroleum storage tanks. Other sources of MTBE include atmospheric deposition, stormwater runoff, watercraft and residential usage of fuels. EPA reports MTBE has been widely found in ground and surface water across the country.

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